This invention relates to esophageal probes, and more particularly to an esophageal probe for performing recording, monitoring or stimulation functions from or within the esophagus, such as transesophageal monitoring of cardiac activity, transesophageal cardiac stimulation, such as cardiac pacing, or esophageal oximetry.
Esophageal probes are known in the art for performing various functions, such as cardiac monitoring, recording, pacing or electroversion. An esophageal probe may be in the form of an esophageal stethoscope which includes a diaphragm for listening to heart and breath sounds, and may incorporate a thermistor sensor for monitoring body temperature. An esophageal stethoscope may also be used for esophageal oximetry, in which oximetry measurements are obtained via oximetry probes in proximity to mucosal tissues within the esophagus.
Prior art esophageal probes used for transesophageal atrial pacing (TAP) applications typically incorporate either ring electrodes or point contact-type electrodes. In either version, the electrodes are fixed to the tubular wall of the probe, and wire leads extend through the internal passage of the probe and terminate in an external connector for coupling to a pacing apparatus. An example of a ring-type pacing probe is available from Cardio Command, Inc. of Tampa, Fla. under the designation TAPSCOPE.
Prior art esophageal oximetry probes typically include oximetry sensors mounted to a contoured structure secured to the tubular wall of the probe. The contoured structure is adapted for placement in a predetermined region within the esophagus of a patient, such that the oximetry probes are in close proximity to, or in contact with, the muscosal tissues of the esophagus in order to provide an accurate oximetry reading. Various satisfactory contoured structures are known, and examples are shown in U.S. Pat. Nos. 5,715,816 and 5,743,261, the disclosures of which are hereby incorporated by reference. Again, the oximetry sensors are interconnected with wire leads which are located within the internal passage of the probe and which terminate in a connector for coupling to an oximetry apparatus.
The above-described prior art esophageal probes have been found to provide satisfactory functions in listening to heart and breath sounds of a patient as well as for carrying out TAP and oximetry functions. Manufacture of TAP probes is complicated by mounting of the electrodes to the wall of the probe and placing the wire leads of the electrodes within the passage of the probe. The same holds true for oximetry probes, which require mounting of a contoured structure to the tubular probe and placement of the wire leads from the oximetry sensors within the passage of the probe. Accordingly, such probes are expensive and difficult to manufacture, and have met with limited acceptance by practitioners.
It is an object of the present invention to provide an esophageal probe, which preferably includes an acoustic pick-up and a thermistor element, and which provides capabilities for oximetry and/or cardiac pacing or other recording, monitoring or stimulation functions from or within the esophagus. It is a further object of the invention to provide such an esophageal probe which provides the basic capability of listening to heart and breath sounds and which also can be used for cardiac pacing, oximetry or other esophageal recording, monitoring and/or stimulation functions. Yet another object of the invention is to provide such an esophageal probe which is simple in its construction and which provides a high degree of flexibility in performing esophageal recording, monitoring and stimulation functions. A still further object of the invention is to provide such an esophageal probe which is relatively low in cost and simple in its components, assembly and operation. Yet another object of the invention is to provide such an esophageal probe which can be easily and quickly fitted with components for use in carrying esophageal recording, monitoring or stimulation functions.
In accordance with the invention, an esophageal probe generally includes a tubular flexible body having a proximal end and a distal end which is adapted to be placed into the esophagus of a patient. The probe may be in the form of an esophageal stethoscope, wherein the tubular flexible body includes an acoustic input region located toward the distal end for communicating heart and breath sounds through the tubular flexible body to the proximal end. The invention contemplates a carrier member, separate from the tubular flexible body, which is engageable with the tubular flexible body toward the distal end. The carrier member includes one or more accessories, devices or components for recording, monitoring and/or stimulating a condition within or from the esophagus of a patient. The carrier member defines a passage within which a portion of the tubular flexible body is received, for engaging the carrier member with the tubular flexible body. The carrier member may be in the form of a channel-type member having wall structure defining the passage and terminating in a pair of spaced apart ends. The space between the ends of the wall structure is in communication with the passage, and the tubular flexible body is adapted to pass through the space and into the passage. The wall structure may be formed of a resilient material, such that the spaced apart ends of the wall structure can be moved away from each other to allow the tubular flexible body to pass into the passage, and to thereafter allow the wall structure to move back together so as to engage the tubular flexible body.
Retainer structure is preferably interposed between the carrier member and the tubular flexible body for maintaining the carrier member in a desired axial position on the tubular flexible body. The retainer structure may be in the form of an opening formed in a wall of the tubular flexible body, and an engagement member associated with the carrier member and receivable within the opening in the wall of the tubular flexible body. In another form, the tubular flexible body is provided with one or more outward protrusion areas engageable with the carrier member. The outward protrusion areas may be in the form of one or more ring members, which may be engageable with the ends of the carrier member or received within a groove formed in an internal wall of the carrier member which defines the passage, for maintaining the carrier member in a predetermined axial position on the tubular flexible body. The ring member may be formed integrally with the wall of the tubular flexible body, or may be separate from and engageable with the wall of the tubular flexible body.
In one form, the carrier member carries a series of electrodes for use in transesophageal cardiac pacing and electrocardiography (ECG). The carrier member is preferably engaged with the tubular flexible body at a distal location relative to the acoustic input region, so as to preserve acoustic function while at the same time providing optimal positioning of the electrodes for use in cardiac pacing. The electrodes extend outwardly from an external surface defined by the carrier member, and each electrode is interconnected with one or more wire leads disposed within grooves or passages defined by the carrier member. The wire leads extend from a proximal end of the carrier member, and are located exteriorly of the tubular flexible body. The leads are preferably secured to the tubular flexible body, and terminate in a connector for coupling to a transesophageal or esophageal monitor and stimulator. In this manner, a basic esophageal stethoscope can be fitted for a cardiac pacing, ECG or other stimulation application such as DC cardioversion/defibrillation.
In another form, the carrier member carries an oximetric device such as one or more optodes (photoemitters, photodetectors) or the like. In this form, the carrier member is engaged with the tubular flexible body at a proximal location relative to the acoustic pick-up region, so as to place the optodes at an optimal location within the esophagus for obtaining oximetry readings. The carrier member may be in the form of a contoured member corresponding to the configuration of mucosal tissues within the esophagus, for placing the optodes in close proximity to the mucosal tissues. The optodes may be mounted to a deformable area associated with the carrier member located over a recess, with an inflatable member being located within the recess. In this manner, inflation of the inflatable member functions to outwardly deform the deformable area so as to contact the optodes with the mucosal tissues of the esophagus, to obtain accurate oximetry inputs. Alternatively, each of a pair of optodes may be mounted to a separate deformable area located over one of a pair of recesses. An inflatable member is located within each recess, and inflation of the inflatable members deforms the deformable areas such that the optodes face each other with mucosal tissues therebetween, to provide highly accurate oximetry readings. The optodes may be designed to carry out either transmissive oximetry or reflectance oximetry.
With this construction, an esophageal stethoscope can be provided with either stimulation or pacing capabilities or oximetry or other monitoring or recording capabilities, or both, simply by engaging either a stimulation carrier or a monitoring/recording carrier, or both, with the tubular flexible body of the esophageal stethoscope. This allows a user to customize the capabilities of an esophageal probe according to the needs of a particular patient. This also provides a manufacturer with significant flexibility in manufacture and production, by utilizing a basic stethoscope structure with add-on capabilities. A stethoscope can thus be used for a wide variety of applications with on-site adaptations according to patient requirements and other criteria. This reduces the overall cost and complexity of esophageal stethoscope assemblies, thus lowering production costs, while providing a wide variety of capabilities for the stethoscope and a wide variety of end use applications.
The invention further contemplates a method of adapting an esophageal stethoscope for use in carrying out various recording, monitoring and/or stimulation functions, as well as an esophageal stethoscope for receiving one or more carrier members adapted to provide esophageal recording, monitoring, or stimulation functions, substantially as summarized above.